KR20210078065A - Grain oriented electrical steel sheet and method of manufacturing the same - Google Patents

Grain oriented electrical steel sheet and method of manufacturing the same Download PDF

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KR20210078065A
KR20210078065A KR1020190169752A KR20190169752A KR20210078065A KR 20210078065 A KR20210078065 A KR 20210078065A KR 1020190169752 A KR1020190169752 A KR 1020190169752A KR 20190169752 A KR20190169752 A KR 20190169752A KR 20210078065 A KR20210078065 A KR 20210078065A
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grain
steel sheet
oriented electrical
electrical steel
temperature
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KR1020190169752A
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KR102305718B1 (en
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박창수
한규석
박유준
서진욱
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주식회사 포스코
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Priority to KR1020190169752A priority Critical patent/KR102305718B1/en
Priority to JP2022536951A priority patent/JP7465975B2/en
Priority to EP20901021.4A priority patent/EP4079886A4/en
Priority to US17/786,267 priority patent/US20230029310A1/en
Priority to CN202080087113.3A priority patent/CN114829657B/en
Priority to PCT/KR2020/018330 priority patent/WO2021125738A1/en
Publication of KR20210078065A publication Critical patent/KR20210078065A/en
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Abstract

The present invention relates to an oriented electric steel plate and a manufacturing method thereof. According to one embodiment of the present invention, the oriented electric steel plate includes: 3.0-4.5 wt% of Si; 0.05-0.2 wt% of Mn; 0.015-0.035 wt% of Al; no more than 0.0015 wt% (excluding 0) of C; no more than 0.0015 wt% (excluding 0) of N; no more than 0.0015 wt% (excluding 0) of S; and the remaining of Fe and inevitable impurities. The oriented electric steel plate satisfies the following relational expressions 1 and 2. Relational expression 1 is (W13/50/W17/50) <= 0.57, and relational expression 2 is W15/50/W17/50) <= 0.76. Here, in the relational expression 1, Wx/y refers to an iron loss value on a frequency yHz condition with an applied magnetic field having a size of x/10T.

Description

방향성 전기강판 및 그 제조방법{GRAIN ORIENTED ELECTRICAL STEEL SHEET AND METHOD OF MANUFACTURING THE SAME}Grain-oriented electrical steel sheet and its manufacturing method {GRAIN ORIENTED ELECTRICAL STEEL SHEET AND METHOD OF MANUFACTURING THE SAME}

본 발명은 방향성 전기강판 및 그 제조방법에 관한 것이다.The present invention relates to a grain-oriented electrical steel sheet and a method for manufacturing the same.

방향성 전기강판은 강판의 결정방위가 {110}<001>인 일명 고스(Goss) 방위를 갖는 결정립들로 이루어진 압연방향으로의 자기적 특성이 뛰어난 연자성 재료이다. The grain-oriented electrical steel sheet is a soft magnetic material having excellent magnetic properties in the rolling direction, which is made of grains having a so-called Goss orientation in which the crystal orientation of the steel sheet is {110}<001>.

일반적으로 자기특성은 자속밀도와 철손으로 표현될 수 있으며, 높은 자속밀도는 결정립의 방위를 {110}<001>방위에 정확하게 배열함으로서 얻어질 수 있다. 자속밀도가 높은 전기강판은 전기기기의 철심재료의 크기를 작게 할 수 있을 뿐만 아니라 이력손실(Hysteresis loss)이 낮아져서 전기기기의 소형화와 동시에 고효율화를 높일 수 있다. 철손은 강판에 임의의 교류자장을 가하였을 때 열에너지로서 소비되는 전력손실로서, 강판의 자속밀도와 판두께, 강판중의 불순물량, 비저항 그리고 2차재결정립 크기 등에 의해서 크게 변화하며, 자속밀도와 비저항이 높을수록 그리고 판두께와 강판 중의 불순물량이 낮을수록 철손이 낮아져 전기기기의 효율이 증가하게 된다. In general, magnetic properties can be expressed in terms of magnetic flux density and iron loss, and high magnetic flux density can be obtained by accurately arranging grain orientations in {110}<001> orientations. Electrical steel sheet with high magnetic flux density can reduce the size of the iron core material of electrical equipment, as well as reduce hysteresis loss, so that it is possible to miniaturize electrical equipment and increase efficiency at the same time. Iron loss is the power loss consumed as thermal energy when an arbitrary AC magnetic field is applied to the steel sheet. It varies greatly depending on the magnetic flux density and thickness of the steel sheet, the amount of impurities in the steel sheet, specific resistance, and secondary recrystallization grain size. The higher the resistivity and the lower the plate thickness and the amount of impurities in the steel plate, the lower the iron loss and the efficiency of the electrical equipment increases.

고스 방위를 발달시키기 위해서는 제강단계에서의 성분제어에서부터 열간압연, 열연판소둔, 냉간압연, 1차 소둔 및 2차 소둔 등의 여러 공정조건들이 매우 정밀하고 엄격하게 관리되어야 한다.In order to develop Goss orientation, various process conditions such as component control in the steelmaking stage, hot rolling, hot-rolled sheet annealing, cold rolling, primary annealing and secondary annealing, must be managed very precisely and strictly.

특히, 고스 방위의 성장은 2차 소둔 단계에서 일어나게 되는데, 강판 중에 분산해 있는 인히비터(Inhibitor) 성분에 의해 성장이 억제되어 있는 다른 결정들을 침식해서 (110)<001> 결정이 우선 성장(2차 재결정)된다.In particular, the growth of the Goss orientation occurs in the secondary annealing step, and the (110)<001> crystals are first grown (2) by eroding other crystals whose growth is suppressed by the inhibitor component dispersed in the steel sheet (2). car recrystallization).

일반적으로 고스 방위를 안정적으로 강하게 발달시키기 위해서는 승온구간에서 2차 재결정 개시온도까지 느린 속도로 승온을 하는 것이 바람직한 것으로 알려져 있다.In general, in order to stably and strongly develop the Goss orientation, it is known that it is desirable to increase the temperature at a slow rate from the temperature increase section to the secondary recrystallization start temperature.

그러나, 2차 소둔 승온과정에서 승온 속도를 늦추게 되면 고스 방위의 결정 크기가 매우 조대해지는데, 고스 방위의 결정 크기가 커질수록 자구크기 증가에 따른 와류손실(Eddy-current loss)의 증가로 철손 특성이 열위해질 가능성이 있다.However, if the temperature increase rate is slowed in the secondary annealing process, the crystal size of the Goss orientation becomes very coarse. As the crystal size of the Goss orientation increases, the iron loss due to the increase in eddy-current loss due to the increase in the magnetic domain size. There is a possibility that the characteristics will be inferior.

특히, 인가하는 자장의 크기가 감소할수록 그 영향이 크게 나타나므로, 방향성 전기강판 제품의 특성을 보증하는 1.7T에서의 철손 값보다 실제 변압기가 동작하는 1.5T 이하의 영역에서의 손실 체감효과가 더 크게 증가한다.In particular, as the magnitude of the applied magnetic field decreases, the effect becomes larger, so the effect of diminishing loss in the area below 1.5T in which the actual transformer operates is greater than the iron loss value at 1.7T, which guarantees the characteristics of grain-oriented electrical steel sheet products. greatly increases

따라서, 단순히 2차 소둔 승온과정에서의 승온 속도를 늦추는 것만으로는 저자장 특성이 우수한 동시에 높은 자속밀도를 갖는 방향성 전기강판 제조에 어려움이 있다.Therefore, it is difficult to manufacture a grain-oriented electrical steel sheet having excellent low magnetic field characteristics and high magnetic flux density by simply slowing the temperature increase rate in the secondary annealing process.

본 발명의 일측면은, 저자장 특성이 우수한 동시에 높은 자속밀도를 갖는 방향성 전기강판 및 그 제조 방법을 제공하고자 하는 것이다.One aspect of the present invention is to provide a grain-oriented electrical steel sheet having excellent low magnetic field characteristics and high magnetic flux density and a method for manufacturing the same.

본 발명의 일 실시형태는 중량%로, Si: 3.0~4.5%, Mn: 0.05~0.2%, Al: 0.015~0.035%, C: 0.0015% 이하(0%는 제외), N: 0.0015% 이하(0%는 제외) 및 S: 0.0015% 이하(0%는 제외), 잔부 Fe 및 기타 불가피한 불순물을 포함하며, 하기 관계식 1 및 2를 만족하는 방향성 전기강판을 제공한다.One embodiment of the present invention is by weight%, Si: 3.0 to 4.5%, Mn: 0.05 to 0.2%, Al: 0.015 to 0.035%, C: 0.0015% or less (excluding 0%), N: 0.0015% or less ( Except for 0%) and S: 0.0015% or less (excluding 0%), the balance includes Fe and other unavoidable impurities, and provides a grain-oriented electrical steel sheet satisfying the following Relations 1 and 2.

[관계식 1] (W13/50/W17/50) ≤ 0.57 [Relational Expression 1] (W 13/50 /W 17/50 ) ≤ 0.57

[관계식 2] (W15/50/W17/50) ≤ 0.76 [Expression 2] (W 15/50 / W 17/50 ) ≤ 0.76

(단, 상기 관계식 1에서 Wx/y는 인가자장의 크기가 x/10T이고, 주파수 yHz 조건에서의 철손값을 나타낸다.)(However, in Relation 1, Wx/y represents an iron loss value under the condition that the magnitude of the applied magnetic field is x/10T and the frequency yHz.)

본 발명의 다른 실시형태는 중량%로, Si: 3.0~4.5%, Mn: 0.05~0.2%, Al: 0.015~0.035%, C: 0.005~0.1%, N: 0.005% 이하(0%는 제외) 및 S: 0.005% 이하(0%는 제외), 잔부 Fe 및 기타 불가피한 불순물을 포함하는 강 슬라브를 가열하는 단계; 상기 가열된 강 슬라브를 열간압연하여 열연판을 얻는 단계; 상기 열연판을 냉간압연하여 냉연판을 얻는 단계; 상기 냉연판을 1차 재결정 소둔하는 단계; 및 상기 1차 재결정 소둔된 냉연판을 2차 재결정 소둔하는 단계;를 포함하며, 상기 2차 재결정 소둔하는 단계는 승온 및 균열 단계를 포함하고, 상기 승온 단계는 1차 승온 및 2차 승온을 포함하며, 상기 1차 승온 및 2차 승온시, 1차 승온 속도와 2차 승온 속도는 하기 관계식 3을 만족하고, 상기 1차 승온 속도는 5~15℃/hr이며, 상기 균열시, 1150℃ 이상에서 10시간 이상 유지하는 방향성 전기강판의 제조방법을 제공한다.Another embodiment of the present invention is by weight%, Si: 3.0 to 4.5%, Mn: 0.05 to 0.2%, Al: 0.015 to 0.035%, C: 0.005 to 0.1%, N: 0.005% or less (excluding 0%) and S: 0.005% or less (excluding 0%), heating the steel slab containing the remainder Fe and other unavoidable impurities; obtaining a hot-rolled sheet by hot rolling the heated steel slab; cold-rolling the hot-rolled sheet to obtain a cold-rolled sheet; primary recrystallization annealing the cold-rolled sheet; and secondary recrystallization annealing of the cold-rolled sheet subjected to the primary recrystallization annealing, wherein the secondary recrystallization annealing includes a temperature raising and cracking step, and the temperature raising step includes a primary temperature increase and a secondary temperature increase and, at the time of the first temperature increase and the second temperature increase, the first temperature increase rate and the second temperature increase rate satisfy the following relation 3, the first temperature increase rate is 5-15 ° C / hr, and at the time of the cracking, 1150 ° C or more To provide a method of manufacturing a grain-oriented electrical steel sheet maintained for 10 hours or more.

[관계식 3] (1차 승온 속도) ≥ 2×(2차 승온 속도)[Relational Expression 3] (1st temperature increase rate) ≥ 2×(2nd temperature increase rate)

본 발명의 일측면에 따르면, 저자장 특성이 우수한 동시에 높은 자속밀도를 갖는 방향성 전기강판 및 그 제조 방법을 제공할 수 있다.According to one aspect of the present invention, it is possible to provide a grain-oriented electrical steel sheet having excellent low magnetic field characteristics and high magnetic flux density and a method for manufacturing the same.

이하, 본 발명의 일 실시형태에 따른 방향성 전기강판에 대하여 설명한다. 본 발명의 일 실시형태에 따른 방향성 전기강판은 중량%로, Si: 3.0~4.5%, Mn: 0.05~0.2%, Al: 0.015~0.035%, C: 0.0015% 이하(0%는 제외), N: 0.0015% 이하(0%는 제외) 및 S: 0.0015% 이하(0%는 제외), 잔부 Fe 및 기타 불가피한 불순물을 포함하며, 하기 관계식 1 및 2를 만족하는 방향성 전기강판을 제공한다.Hereinafter, a grain-oriented electrical steel sheet according to an embodiment of the present invention will be described. Grain-oriented electrical steel sheet according to an embodiment of the present invention by weight%, Si: 3.0 to 4.5%, Mn: 0.05 to 0.2%, Al: 0.015 to 0.035%, C: 0.0015% or less (excluding 0%), N : 0.0015% or less (excluding 0%) and S: 0.0015% or less (excluding 0%), the balance Fe and other unavoidable impurities, and provides a grain-oriented electrical steel sheet satisfying the following Relations 1 and 2.

[관계식 1] (W13/50/W17/50) ≤ 0.57 [Relational Expression 1] (W 13/50 /W 17/50 ) ≤ 0.57

[관계식 2] (W15/50/W17/50) ≤ 0.76 [Expression 2] (W 15/50 / W 17/50 ) ≤ 0.76

(단, 상기 관계식 1에서 Wx/y는 인가자장의 크기가 x/10T이고, 주파수 yHz 조건에서의 철손값을 나타낸다.)(However, in Relation 1, Wx/y represents an iron loss value under the condition that the magnitude of the applied magnetic field is x/10T and the frequency yHz.)

본 발명의 방향성 전기강판은 상기 관계식 1 및 2를 만족함으로써 우수한 저자장 철손을 확보할 수 있을 뿐만 아니라, 1.94T(tesla) 이상의 우수한 자속밀도를 확보할 수 있어, 결과적으로 우수한 자기특성을 확보할 수 있다. The grain-oriented electrical steel sheet of the present invention can not only secure excellent low-field iron loss by satisfying the above Relations 1 and 2, but also secure excellent magnetic flux density of 1.94T (tesla) or more, resulting in excellent magnetic properties. can

아울러, 본 발명의 방향성 전기강판은 압연면을 기준으로 입자 지름 100mm 이상인 결정립이 차지하는 면적 비율이 20% 이하인 것이 바람직하다. 고스 방위의 입자 지름이 증가하면 자구 간격이 증가하여 저자장에서의 자화특성이 떨어지게 되며, 저자장 철손을 열화시키게 된다. 특히, 2차 재결정 소둔 단계에서 승온 속도가 감소하면 코일 상부에서 온도 구배가 발생하여 입자 크기가 100mm 이상인 조대립의 분율이 증가하게 되는데, 이러한 조대립이 저자장 철손 열화에 큰 영향을 미치게 된다. 따라서, 압연면을 기준으로 입자 지름 100mm 이상인 결정립이 차지하는 면적 비율은 20% 이하인 것이 바람직하다. 본 발명에서 언급하는 압연면이란 강판의 판면을 의미한다.In addition, in the grain-oriented electrical steel sheet of the present invention, it is preferable that the area ratio occupied by crystal grains having a particle diameter of 100 mm or more based on the rolled surface is 20% or less. When the particle diameter of the Goss orientation increases, the magnetic domain spacing increases, and the magnetization characteristic in the low field deteriorates, and the iron loss in the low field deteriorates. In particular, when the temperature increase rate is decreased in the secondary recrystallization annealing step, a temperature gradient occurs at the top of the coil, and the fraction of coarse grains having a particle size of 100 mm or more increases. Therefore, it is preferable that the area ratio occupied by the crystal grains having a particle diameter of 100 mm or more based on the rolling surface is 20% or less. The rolled surface referred to in the present invention means the plate surface of the steel sheet.

이하, 본 발명의 방향성 전기강판을 제조하기 위한 방법의 일 실시형태에 대하여 설명한다. 본 발명의 일 실시형태에 따른 방향성 전기강판의 제조방법은 중량%로, Si: 3.0~4.5%, Mn: 0.05~0.2%, Al: 0.015~0.035%, C: 0.005~0.1%, N: 0.005% 이하(0%는 제외) 및 S: 0.005% 이하(0%는 제외), 잔부 Fe 및 기타 불가피한 불순물을 포함하는 강 슬라브를 가열하는 단계; 상기 가열된 강 슬라브를 열간압연하여 열연판을 얻는 단계; 상기 열연판을 냉간압연하여 냉연판을 얻는 단계; 상기 냉연판을 1차 재결정 소둔하는 단계; 및 상기 1차 재결정 소둔된 냉연판을 2차 재결정 소둔하는 단계;를 포함하며, 상기 2차 재결정 소둔하는 단계는 승온 및 균열 단계를 포함하고, 상기 승온 단계는 1차 승온 및 2차 승온을 포함하며, 상기 1차 승온 및 2차 승온시, 1차 승온 속도와 2차 승온 속도는 하기 관계식 3을 만족하고, 상기 1차 승온 속도는 5~15℃/hr이며, 상기 균열시, 1150℃ 이상에서 10시간 이상 유지하는 것을 포함한다.Hereinafter, an embodiment of a method for manufacturing a grain-oriented electrical steel sheet of the present invention will be described. The method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention is by weight %, Si: 3.0 to 4.5%, Mn: 0.05 to 0.2%, Al: 0.015 to 0.035%, C: 0.005 to 0.1%, N: 0.005 % or less (excluding 0%) and S: 0.005% or less (excluding 0%), heating the steel slab containing the remainder Fe and other unavoidable impurities; obtaining a hot-rolled sheet by hot rolling the heated steel slab; cold-rolling the hot-rolled sheet to obtain a cold-rolled sheet; primary recrystallization annealing the cold-rolled sheet; and secondary recrystallization annealing of the cold-rolled sheet subjected to the primary recrystallization annealing, wherein the secondary recrystallization annealing includes a temperature raising and cracking step, and the temperature raising step includes a primary temperature increase and a secondary temperature increase and, at the time of the first temperature increase and the second temperature increase, the first temperature increase rate and the second temperature increase rate satisfy the following relation 3, the first temperature increase rate is 5-15 ° C / hr, and at the time of the cracking, 1150 ° C or more Including holding for more than 10 hours in

[관계식 3] (1차 승온 속도) ≥ 2×(2차 승온 속도)[Relational Expression 3] (1st temperature increase rate) ≥ 2×(2nd temperature increase rate)

먼저, 합금조성에 대하여 설명한다. 하기 설명되는 방향성 전기강판의 합금조성의 단위는 특별한 언급이 없는 한 중량%를 의미한다.First, the alloy composition will be described. The unit of the alloy composition of the grain-oriented electrical steel sheet to be described below means wt% unless otherwise specified.

Si: 3.0~4.5%Si: 3.0~4.5%

실리콘(Si)은 전기강판의 기본 조성으로 소재의 비저항을 증가시켜 철손을 개선하는 역할을 한다. Si이 3.0% 미만일 경우에는 비저항이 감소와 더불어 와전류손이 증가하여 철손특성이 열위하게 되는 단점이 있다. 반면, Si이 4.5%를 초과하는 경우에는 기계적 특성 중 연성과 인성이 감소하여 압연 과정중 판파단이 빈번하게 발생할 뿐만 아니라, 상업적 생산을 위한 연속소둔시 판간 용접성이 열위하게 되어 생산성이 악화되는 단점이 있다. 따라서, 상기 Si의 함량은 3.0~4.5%의 범위를 갖는 것이 바람직하다. 상기 Si 함량의 하한은 3.1%인 것이 보다 바람직하고, 3.3%인 것이 보다 더 바람직하다. 상기 Si 함량의 상한은 4.0%인 것이 보다 바람직하고, 3.8%인 것이 보다 더 바람직하다.Silicon (Si) serves to improve iron loss by increasing the specific resistance of the material as the basic composition of the electrical steel sheet. When Si is less than 3.0%, the specific resistance decreases and eddy current loss increases, resulting in inferior iron loss characteristics. On the other hand, when Si exceeds 4.5%, ductility and toughness are reduced among mechanical properties, and plate fractures occur frequently during the rolling process, as well as poor weldability between plates during continuous annealing for commercial production, resulting in deterioration of productivity. There is this. Accordingly, the Si content is preferably in the range of 3.0 to 4.5%. The lower limit of the Si content is more preferably 3.1%, and even more preferably 3.3%. The upper limit of the Si content is more preferably 4.0%, even more preferably 3.8%.

Mn: 0.05~0.2%Mn: 0.05~0.2%

망간(Mn)은 Si와 동일하게 비저항을 증가시켜 와전류손을 감소시킴으로써 철손을 감소시키는 효과가 있을 뿐만 아니라, 강중에 존재하는 S와 반응하여 Mn계 화합물을 형성하거나 Al, Si 및, N 이온과 반응하여 (Al,Si,Mn)N 형태의 질화물을 형성함으로써 결정립 성장 억제제를 형성하는 역할을 한다. 상기 Mn의 함량이 0.05% 미만인 경우에는 상기 효과를 기대할 수 없으며, 0.2%를 초과하는 경우에는 2차 재결정 소둔 중 오스테나이트 상변태율이 증가하여 고스집합조직이 심각하게 훼손되어 자기적 특성이 급격히 저하될 수 있다. 따라서, 상기 Mn의 함량은 0.05~0.2%의 범위를 갖는 것이 바람직하다. 상기 Mn 함량의 하한은 0.08%인 것이 보다 바람직하고, 0.1%인 것이 보다 더 바람직하다. 상기 Mn 함량의 상한은 0.18%인 것이 보다 바람직하고, 0.15%인 것이 보다 더 바람직하다.Manganese (Mn) not only has the effect of reducing iron loss by reducing eddy current loss by increasing specific resistance in the same way as Si, but also reacts with S present in steel to form Mn-based compounds, or with Al, Si and N ions. It acts to form a grain growth inhibitor by reacting to form a nitride in the form of (Al,Si,Mn)N. When the content of Mn is less than 0.05%, the above effect cannot be expected, and when it exceeds 0.2%, the austenite phase transformation rate increases during the secondary recrystallization annealing, and the Goss texture is severely damaged and the magnetic properties are rapidly reduced. can be Therefore, the Mn content is preferably in the range of 0.05 to 0.2%. The lower limit of the Mn content is more preferably 0.08%, even more preferably 0.1%. The upper limit of the Mn content is more preferably 0.18%, even more preferably 0.15%.

Al: 0.015~0.035%Al: 0.015~0.035%

알루미늄(Al)은 탈탄질화소둔 과정 중 분위기 가스인 암모니아 가스에 의하여 도입된 N 이온과 결합하여 AlN 형태의 질화물을 형성할 뿐만 아니라, 강중에 고용상태로 존재하는 Si, Mn 및, N 이온과 결합하여 (Al,Si,Mn)N 형태의 질화물을 형성함으로써 결정립 성장 억제제를 형성하는 역할을 한다. 상기 Al의 함량이 0.015% 미만인 경우에는 상기 효과를 기대할 수 없으며, 상기 Al의 함량이 0.035%를 초과하는 경우에는 매우 조대한 질화물을 형성함으로써 결정립 성장 억제력이 급격히 저하될 수 있다. 따라서, 상기 Al의 함량은 0.015~0.035%의 범위를 갖는 것이 바람직하다. 상기 Al 함량의 하한은 0.023%인 것이 보다 바람직하고, 0.028%인 것이 보다 더 바람직하다. 상기 Al 함량의 상한은 0.033%인 것이 보다 바람직하고, 0.031%인 것이 보다 더 바람직하다.Aluminum (Al) is combined with N ions introduced by ammonia gas, which is an atmospheric gas, during the decarburization annealing process to form an AlN nitride, as well as Si, Mn, and N ions present in a solid solution in the steel. It serves to form a grain growth inhibitor by forming a nitride in the form of (Al, Si, Mn)N. When the Al content is less than 0.015%, the above effect cannot be expected, and when the Al content exceeds 0.035%, a very coarse nitride is formed, so that the grain growth inhibitory power may be rapidly reduced. Accordingly, the Al content is preferably in the range of 0.015 to 0.035%. The lower limit of the Al content is more preferably 0.023%, even more preferably 0.028%. The upper limit of the Al content is more preferably 0.033%, and even more preferably 0.031%.

C: 0.005~0.1%C: 0.005~0.1%

탄소(C)은 오스테나이트 안정화 원소로서, 슬라브 중에 첨가되어 연주과정에 발생하는 조대한 주상조직을 미세화하고 S의 슬라브 중심편석을 억제하는 역할을 한다. 또한, 냉간압연 중에 강판의 가공경화를 촉진하여 강판 내에 {110}<001>방위의 2차 재결정 핵 생성을 촉진하는 역할을 하기도 한다. 그러나, 상기 C의 함량이 0.005% 미만인 경우에는 상기 효과를 충분히 기대하기 어려우며, 0.1%를 초과하는 경우에는 강판 내부의 탄화물이 증가하여 냉간압연 특성을 열위시킬 수 있다. 이에 따라, 상기 C의 함량은 0.005~0.1%의 범위를 갖는 것이 바람직하다. 상기 C 함량의 하한은 0.03%인 것이 보다 바람직하고, 0.05%인 것이 보다 더 바람직하다. 상기 C 함량의 상한은 0.8%인 것이 보다 바람직하고, 0.65%인 것이 보다 더 바람직하다. 한편, 최종적으로 얻어지는 방향성 전기강판에 포함되는 C는 자기 시효를 유발하여 자속밀도 및 저자장 특성을 악화시키므로, 전기강판의 제조 과정에서 탈탄 소둔을 거치게 되며, 이러한 탈탄 소둔을 거쳐 최종적으로 얻어지는 방향성 전기강판 내의 C 함량은 0.0015%이하인 것이 바람직하다.Carbon (C) is an austenite stabilizing element, which is added in the slab to refine the coarse columnar structure generated during the casting process and suppresses the segregation of S in the slab. In addition, it also serves to promote work hardening of the steel sheet during cold rolling to promote secondary recrystallization nucleation in the {110}<001> orientation in the steel sheet. However, when the content of C is less than 0.005%, it is difficult to sufficiently expect the above effect, and when it exceeds 0.1%, carbides inside the steel sheet increase and the cold rolling characteristics may be inferior. Accordingly, the content of C is preferably in the range of 0.005 to 0.1%. The lower limit of the C content is more preferably 0.03%, and even more preferably 0.05%. The upper limit of the C content is more preferably 0.8%, and even more preferably 0.65%. On the other hand, since C contained in the grain-oriented electrical steel sheet finally obtained causes magnetic aging to deteriorate magnetic flux density and low magnetic field characteristics, it undergoes decarburization annealing in the manufacturing process of the electrical steel sheet, and grain-oriented electricity finally obtained through such decarburization annealing The C content in the steel sheet is preferably 0.0015% or less.

N: 0.005% 이하(0%는 제외)N: 0.005% or less (excluding 0%)

질소(N)은 Si, Al 및 Mn과 반응하여 AlN 및 (Al,Si,Mn)N 등의 화합물을 형성하는 중요한 원소이며, 슬라브 내에 0.005% 이하로 포함할 수 있다. 다만, 상기 N의 함량이 0.005%를 초과하는 경우에는 열연 이후의 공정에서 질소확산에 의한 blister와 같은 표면결함을 유발하게 될 뿐만 아니라, 슬라브 상태에서 과잉의 질화물이 형성되기 때문에 압연이 용이하지 못해, 제조단가가 상승하는 원인이 된다. 따라서, 상기 N의 함량은 0.005% 이하(0%는 제외)의 범위를 갖는 것이 바람직하다. 상기 N 함량의 하한은 0.002%인 것이 보다 바람직하고, 0.003%인 것이 보다 더 바람직하다. 상기 N 함량의 상한은 0.0045%인 것이 보다 바람직하고, 0.0040%인 것이 보다 더 바람직하다. 한편, 고스집합조직의 2차재결정 형성을 위한 질화물의 보강은 탈탄소둔공정 중 암모니아 가스를 분위기 가스로 도입함으로써 N 이온이 강중에 확산되도록 하는 질화처리를 실시하여 보강한다. 아울러, 상기 N 역시 자기 시효를 일으키는 원소로써, 자속밀도 및 저자장 철손 특성을 열화시킬 수 있으므로, 2차 소둔 공정에서 순화 소둔을 거치게 되고, 이러한 순화 소둔을 거쳐 최종적으로 얻어지는 방향성 전기강판 내 N의 함량은 0.0015%이하인 것이 바람직하다.Nitrogen (N) is an important element that reacts with Si, Al, and Mn to form compounds such as AlN and (Al,Si,Mn)N, and may be included in the slab in an amount of 0.005% or less. However, when the content of N exceeds 0.005%, it not only causes surface defects such as blisters due to nitrogen diffusion in the process after hot rolling, but also makes it difficult to roll because excess nitride is formed in the slab state. , causing the manufacturing cost to rise. Therefore, the content of N is preferably in the range of 0.005% or less (excluding 0%). The lower limit of the N content is more preferably 0.002%, and even more preferably 0.003%. The upper limit of the N content is more preferably 0.0045%, and even more preferably 0.0040%. On the other hand, the reinforcement of the nitride for the formation of secondary recrystallization of the Goss aggregate is reinforced by performing a nitridation treatment that allows N ions to diffuse into the steel by introducing ammonia gas as an atmospheric gas during the decarburization annealing process. In addition, the N is also an element that causes magnetic aging, and since it can deteriorate magnetic flux density and low magnetic field iron loss characteristics, it is subjected to purifying annealing in the secondary annealing process, and the N in the grain-oriented electrical steel sheet finally obtained through such purifying annealing The content is preferably 0.0015% or less.

S: 0.005% 이하(0%는 제외)S: 0.005% or less (excluding 0%)

황(S)는 제조공정상 불가피하게 함유되는 원소이며, 그 함량이 0.005%를 초과하는 경우에는 주조시 슬라브 중심부에 편석하여 취성을 야기하며, 강중의 Mn과 반응하여 Mn계 황화물을 형성하여 미세조직을 불균일하게 하고 압연성을 악화시킨다. 따라서, 상기 S의 함량은 0.005% 이하(0%는 제외)의 범위를 갖는 것이 바람직하다. 상기 S의 함량은 0.0045%이하인 것이 보다 바람직하고, 0.004%이하인 것이 보다 더 바람직하다. 한편, 상기 S 역시 자기 시효를 일으키는 원소로써, 저자장 철손 특성을 개선하기 위하여 2차 소둔 공정에서 순화 소둔을 거치게 되고, 이러한 순화 소둔을 거쳐 최종적으로 얻어지는 방향성 전기강판 내 S 함량은 0.0015%이하인 것이 바람직하다.Sulfur (S) is an element that is unavoidably contained in the manufacturing process, and when its content exceeds 0.005%, it segregates at the center of the slab during casting, causing brittleness, and reacts with Mn in the steel to form Mn-based sulfide to form a microstructure makes it non-uniform and deteriorates the rolling properties. Therefore, the content of S is preferably in the range of 0.005% or less (excluding 0%). The content of S is more preferably 0.0045% or less, and even more preferably 0.004% or less. On the other hand, S is also an element that causes self-aging, and is subjected to purifying annealing in the secondary annealing process in order to improve the low-field iron loss characteristics, and the S content in the grain-oriented electrical steel sheet finally obtained through such purifying annealing is 0.0015% or less. desirable.

본 발명의 방향성 전기강판과 상기 방향성 전기강판의 제조방법에 이용되는 강 슬라브의 나머지 합금성분은 Fe이며, 기타 당해 기술분야에서 불가피하게 함유되는 불순물을 포함할 수 있다.The remaining alloy component of the grain-oriented electrical steel sheet of the present invention and the steel slab used in the method for manufacturing the grain-oriented electrical steel sheet is Fe, and may include other impurities unavoidably contained in the art.

우선, 전술한 바와 같은 합금조성을 갖는 강 슬라브를 가열한다. 상기 강 슬라브시, 가열 온도는 1000~1280℃일 수 있다. 상기 가열 온도 범위로 가열함으로써 슬라브의 주상정 조직이 조대하게 성장하게 되는 것을 방지하여 열간압연 공정에서 판의 크랙이 발생되는 것을 방지할 수 있다. 상기 강 슬라브 가열 온도가 1280℃를 초과하는 경우에는 상기 효과를 충분히 얻기 곤란하며, 1000℃ 미만인 경우에는 주조과정에서 형성된 석출물이 슬라브 과열과정에서 재고용되지 않아 열연 후 매우 조대한 석출물을 만들게 되며, 이로 인해 조직 제어에 불리하게 작용하여 철손 열화를 초래하게 하는 단점이 있다. 상기 강 슬라브 가열 온도의 하한은 1050℃인 것이 보다 바람직하고, 1100℃인 것이 보다 더 바람직하다. 상기 강 슬라브 가열 온도의 상한은 1250℃인 것이 보다 바람직하고, 1200℃인 것이 보다 더 바람직하다.First, a steel slab having an alloy composition as described above is heated. When the steel slab, the heating temperature may be 1000 ~ 1280 ℃. By heating to the heating temperature range, it is possible to prevent the columnar structure of the slab from growing coarsely, thereby preventing cracks in the plate from occurring in the hot rolling process. When the heating temperature of the steel slab exceeds 1280 ℃, it is difficult to sufficiently obtain the effect, and when it is less than 1000 ℃, the precipitates formed in the casting process are not re-dissolved in the slab overheating process. Due to this, there is a disadvantage in that it adversely affects the tissue control and causes iron loss deterioration. As for the lower limit of the said steel slab heating temperature, it is more preferable that it is 1050 degreeC, and it is still more preferable that it is 1100 degreeC. As for the upper limit of the said steel slab heating temperature, it is more preferable that it is 1250 degreeC, and it is still more preferable that it is 1200 degreeC.

이후, 상기 가열된 강 슬라브를 열간압연하여 열연판을 얻는다. 본 발명에서는 상기 열간압연 온도에 대해서 특별히 한정하지 않으며, 당해 기술분야에서 통상적으로 이용되는 온도 범위를 적용할 수 있다. 다만, 일례로서, 상기 열간압연시 마무리온도는 950℃ 이하일 수 있다. 상기 열간압연시 마무리온도가 950℃를 초과하는 경우에는 열간압연이 완료된 이후에 상변태가 일어나 집합조직의 열화를 초래할 수 있다. 상기 열간압연을 통해 얻어지는 열연판은 1.5~5.5mm의 두께를 가질 수 있다.Thereafter, the heated steel slab is hot-rolled to obtain a hot-rolled sheet. In the present invention, the hot rolling temperature is not particularly limited, and a temperature range commonly used in the art may be applied. However, as an example, the finishing temperature during the hot rolling may be 950° C. or less. When the finishing temperature during the hot rolling exceeds 950° C., a phase transformation occurs after the hot rolling is completed, which may result in deterioration of the texture. The hot-rolled sheet obtained through the hot rolling may have a thickness of 1.5 to 5.5 mm.

상기 열간압연 후에는, 상기 열연판을 수냉한 뒤, 600℃이하에서 권취할 수 있다. 상기 권취온도가 600℃를 초과할 경우에는 강 내부에 형성된 석출물들의 크기가 커짐에 따라 자성이 나빠지게 될 수 있다.After the hot rolling, the hot-rolled sheet may be cooled in water and then wound at 600° C. or less. When the coiling temperature exceeds 600° C., the magnetism may deteriorate as the size of the precipitates formed inside the steel increases.

한편, 상기 열연판은 필요에 따라 열연판 소둔을 실시하거나 열연판 소둔을 실시하지 않고 냉간압연을 수행할 수 있다. 열연판 소둔을 실시하는 경우 열연조직을 균일하게 만들기 위해서 900℃ 이상의 온도로 가열하고 균열한 다음 냉각할 수 있다.Meanwhile, the hot-rolled sheet may be subjected to hot-rolled sheet annealing or cold-rolled without hot-rolled sheet annealing, if necessary. When hot-rolled sheet annealing is performed, in order to make the hot-rolled structure uniform, it can be heated to a temperature of 900°C or higher, cracked, and then cooled.

이후, 상기 열연판을 냉간압연하여 냉연판을 얻는다. 상기 냉간압연시, 리버스(Reverse) 압연기 혹은 탠덤(Tandom) 압연기를 이용하여 1회의 냉간압연, 다수회의 냉간압연, 또는 중간소둔을 포함하는 다수회의 냉간압연 방법을 이용할 수 있다. 상기 냉간압연을 통해 얻어지는 냉연판은 0.1~0.5mm의 두께를 가질 수 있다. 또한, 상기 냉간압연 중에 강판의 온도를 100℃ 이상으로 유지하는 온간 압연을 실시할 수 있다. 더하여, 상기 냉간압연을 통한 최종 압하율은 50~95%가 될 수 있다.Thereafter, the hot-rolled sheet is cold-rolled to obtain a cold-rolled sheet. During the cold rolling, a plurality of cold rolling methods including one cold rolling, multiple cold rolling, or intermediate annealing may be used using a reverse rolling mill or a tandem rolling mill. The cold-rolled sheet obtained through the cold rolling may have a thickness of 0.1 to 0.5 mm. In addition, during the cold rolling, it is possible to perform warm rolling to maintain the temperature of the steel sheet at 100 ℃ or more. In addition, the final rolling reduction through the cold rolling may be 50 to 95%.

이후, 상기 냉연판을 1차 재결정 소둔한다. 상기 1차 재결정 소둔 단계에서는 고스 결정립의 핵이 생성되는 1차 재결정이 일어난다. 상기 1차 재결정 소둔 과정에서 강판의 탈탄 및 질화가 이루어질 수 있다. 탈탄 및 질화를 위하여 수증기, 수소 및 암모니아의 혼합 가스 분위기 하에서 1차 재결정 소둔할 수 있다. 상기 1차 재결정 소둔은 탈탄을 위해 이슬점 온도가 50~70℃인 분위기에서 850~950℃의 온도로 행하여질 수 있다. 상기 1차 재결정 소둔시, 이슬점 온도가 50℃ 미만인 경우에는 탈탄능이 부족하여 강 중의 탄소를 충분히 제거할 수 없으며, 70℃를 초과하는 경우에는 강판 표면에 Fe 계열의 산화층이 다량 생성되어 최종 제품의 표면 불량을 야기할 수 있다. 상기 1차 재결정 소둔 온도가 850℃ 미만인 경우에는 재결정립들이 미세하게 성장하여 결정성장 구동력이 커짐으로써 안정된 2차 재결정이 일어나지 않을 수 있으며, 950℃를 초과하는 경우에는 재결정립들이 조대하게 성장하여 결정성장 구동력이 떨어져서 안정된 2차 재결정이 일어나지 않을 수 있다. 한편, 상기 1차 재결정 소둔시, 소둔시간은 본 발명에서 특별히 한정하지 않으나, 생산성을 감안하여 통상 5분 이내로 제어할 수 있다. 상기 상기 1차 재결정 소둔시, 질화를 위해 암모니아 가스를 사용하여 강판에 N이온을 도입하여 주석출물인 (Al,Si,Mn)N 및 AlN 등의 질화물을 형성하는데 있어, 탈탄 및 재결정을 마치고 질화처리하거나, 혹은 탈탄과 동시에 질화처리를 행하거나, 혹은 질화처리를 우선 행한 후 탈탄소둔을 행하는 방법 어느 것이나 본 발명의 효과를 발휘하는데 문제가 없다.Thereafter, the cold-rolled sheet is subjected to primary recrystallization annealing. In the primary recrystallization annealing step, primary recrystallization in which Goss grain nuclei are generated occurs. In the primary recrystallization annealing process, decarburization and nitridation of the steel sheet may be performed. For decarburization and nitridation, primary recrystallization annealing may be performed under a mixed gas atmosphere of steam, hydrogen and ammonia. The primary recrystallization annealing may be performed at a temperature of 850 to 950° C. in an atmosphere having a dew point temperature of 50 to 70° C. for decarburization. In the case of the primary recrystallization annealing, when the decarburization ability is insufficient when the decarburization temperature is less than 50°C, carbon in the steel cannot be sufficiently removed. It may cause surface defects. When the primary recrystallization annealing temperature is less than 850°C, the recrystallized grains grow finely and the crystal growth driving force increases, so that stable secondary recrystallization may not occur, and when it exceeds 950°C, the recrystallized grains grow coarsely and crystallize A stable secondary recrystallization may not occur due to a decrease in the growth driving force. On the other hand, during the primary recrystallization annealing, the annealing time is not particularly limited in the present invention, but can be controlled within 5 minutes in consideration of productivity. During the primary recrystallization annealing, N ions are introduced into the steel sheet using ammonia gas for nitriding to form nitrides such as (Al,Si,Mn)N and AlN, which are tin extracts, after decarburization and recrystallization are completed and nitridation is performed. There is no problem in exhibiting the effects of the present invention in any of the methods of treating, performing nitridation at the same time as decarburization, or performing decarburization annealing after nitriding first.

이후, 상기 1차 재결정 소둔된 냉연판을 2차 재결정 소둔한다. 상기 2차 재결정 소둔은 상기 1차 재결정 소둔이 완료된 냉연판에 소둔 분리제를 도포한 후, 소둔하는 방법으로 행하여질 수 있다. 본 발명에서는 상기 소둔 분리제의 종류에 대해서 특별히 한정하지 않으며, 예를 들면, MgO를 주성분으로 포함하는 소둔 분리제를 사용할 수 있다.Thereafter, the cold-rolled sheet subjected to the primary recrystallization annealing is subjected to secondary recrystallization annealing. The secondary recrystallization annealing may be performed by applying an annealing separator to the cold-rolled sheet on which the primary recrystallization annealing has been completed, followed by annealing. In the present invention, the type of the annealing separator is not particularly limited, and, for example, an annealing separator containing MgO as a main component may be used.

상기 2차 재결정 소둔하는 단계는 승온 및 균열 단계를 포함하고, 상기 승온 단계는 1차 승온 및 2차 승온을 포함하며, 상기 1차 승온 및 2차 승온시, 1차 승온 속도와 2차 승온 속도는 하기 관계식 3을 만족하는 것이 바람직하다. 아울러, 상기 1차 승온 속도는 5~15℃/hr이며, 상기 1차 승온시 시작 온도는 700~800℃이고, 상기 2차 승온시 시작 온도는 1000~1100℃이며, 상기 2차 승온시 승온 속도는 7.5℃/hr이하인 것이 바람직하다.The secondary recrystallization annealing step includes a temperature raising and cracking step, and the temperature raising step includes a first temperature increase and a second temperature increase, and when the first temperature increase and the second temperature increase, the first temperature increase rate and the second temperature increase rate preferably satisfies the following relation (3). In addition, the first temperature increase rate is 5 ~ 15 ℃ / hr, the first temperature increase when the starting temperature is 700 ~ 800 ℃, the second temperature increase when the starting temperature is 1000 ~ 1100 ℃, the second temperature rise during the temperature increase The rate is preferably 7.5°C/hr or less.

[관계식 3] (1차 승온 속도) ≥ 2×(2차 승온 속도)[Relational Expression 3] (1st temperature increase rate) ≥ 2×(2nd temperature increase rate)

승온 속도를 두 조건으로 실시하는 이유는 다음과 같다. The reason for carrying out the temperature increase rate under two conditions is as follows.

승온 단계에서는 고스 방위의 2차 재결정이 일어나며, 승온 속도가 느릴수록 {110}<001> 방위와 가까운 고스 결정이 우선성장함에 따라 집적도가 증가하여 자속밀도는 상승하지만, 저온에서부터 2차 재결정이 일어나기 때문에 고스 방위의 결정 크기가 증가하여 저자장 특성은 열화된다. 따라서, AlN 등과 같은 석출물에 의해 고스결정의 성장이 잘 이루어지지 않는 낮은 온도범위에서는 승온 속도를 높이고, AlN이 분해되어 고스결정의 성장이 잘 이루어지는 높은 온도범위에서는 승온 속도를 낮추어, 고스 방위의 집적도는 높이면서 고스 방위의 결정 크기가 조대화되는 것을 억제하는 것이 바람직하다. In the temperature rising step, secondary recrystallization of the Goss orientation occurs, and as the temperature increase rate is slow, as the Goss crystals close to the {110}<001> orientation grow preferentially, the degree of integration increases and the magnetic flux density rises, but secondary recrystallization occurs at low temperatures. For this reason, the crystal size of the Goss orientation increases and the low-field characteristic deteriorates. Therefore, the temperature increase rate is increased in the low temperature range where the growth of Goss crystals is not performed well by the precipitates such as AlN, and the temperature increase rate is lowered in the high temperature range where AlN is decomposed and the Goss crystal growth is well performed, and the degree of integration of the Goss orientation It is desirable to suppress coarsening of the crystal size of the Goss orientation while increasing the .

이를 위해, 본 발명에서는 전술한 바와 같이 상기 2차 재결정 소둔시 승온 속도를 두 단계로 구분하되, 1차 승온시 시작 온도는 700~800℃로 제어하고, 2차 승온시 시작 온도는 1000~1100℃로 제어하는 것이 바람직하다. 상기 1차 승온시 시작 온도가 700℃ 미만인 경우에는 소둔시간이 길어져 생산성이 저하되는 단점이 있고, 800℃를 초과하는 경우에는 소둔분리제에 포함되어 있는 수분이 충분히 제거되지 않은 상태에서 고온으로 올라가게 되어 표면 품질의 열화를 초래할 수 있다. 상기 2차 승온시 시작 온도가 1000℃ 미만인 경우에는 고스 결정립의 크기가 조대해져 저자장 철손 특성이 열위해지며, 1100℃를 초과하는 경우에는 승온 속도가 변하기 전에 이미 고스 방위의 성장이 시작되어 집적도를 제어할 수 없으므로, 높은 자속밀도 특성을 얻을 수가 없다. To this end, in the present invention, as described above, the temperature increase rate during the secondary recrystallization annealing is divided into two stages, but the start temperature during the first temperature increase is controlled to 700 ~ 800 ℃, and the start temperature during the second temperature increase is 1000 ~ 1100 It is preferable to control it at ℃. If the starting temperature is less than 700 ℃ during the first temperature increase, there is a disadvantage in that the annealing time is long and the productivity is lowered, and when it exceeds 800 ℃, the moisture contained in the annealing separator is not sufficiently removed and it rises to a high temperature. This can lead to deterioration of the surface quality. If the starting temperature at the time of the secondary temperature increase is less than 1000 ℃, the size of the Goss crystal grains becomes coarse and the low-field iron loss property is deteriorated, and when it exceeds 1100 ℃, the growth of the Goss orientation is already started before the temperature increase rate changes and the degree of integration can not be controlled, so high magnetic flux density characteristics cannot be obtained.

상기 1차 승온 속도는 5~15℃/hr인 것이 바람직한데, 상기 1차 승온 속도가 5℃/hr 미만인 경우에는 고스 입자의 2차 재결정이 매우 낮은 온도에서부터 일어나기 시작하여 고스 결정방위의 집적도가 열화되며, 15℃/hr를 초과하는 경우에는 코일 내 온도구배가 심화되어 조대립의 분율이 증가할 수 있다. 아울러, 관계식 3과 같이, 1차 승온 속도가 2차 승온 속도보다 두 배 이상 높은 것이 바람직한데, 만일 그렇지 않은 경우에는 낮은 승온속도에 의해 고스방위 결정 성장이 활발히 일어나 안정된 2차 재결정이 일어나지 않을 수 있다.The primary temperature increase rate is preferably 5 ~ 15 ℃ / hr, when the primary temperature increase rate is less than 5 ℃ / hr, the secondary recrystallization of the Goss particles starts to occur from a very low temperature, the degree of integration of the Goss crystal orientation It deteriorates, and when it exceeds 15°C/hr, the temperature gradient in the coil deepens, and the fraction of coarse grains may increase. In addition, as shown in Equation 3, it is preferable that the primary temperature increase rate is twice or more higher than the secondary temperature increase rate. If not, the Goss orientation crystal growth actively occurs due to the low temperature increase rate, so that stable secondary recrystallization may not occur. have.

상기 2차 재결정 소둔 단계에서의 균열 단계는 1150℃ 이상에서 10시간 이상 유지하는 것일 수 있다. 상기 균열 단계는 강 중에 분포하며 자기 시효를 야기하는 C, N 및 S를 제거하는 목적을 갖는 것으로서, 저자장 특성을 개선하기 위해서는 각 성분의 함량이 0.0015중량% 이하로 낮아질 필요가 있다. 만일, 상기 균열 단계시, 균열온도가 1150℃ 미만이거나, 균열시간이 10시간 미만인 경우에는 C, N 및 S의 함량 제어가 곤란할 수 있다.The cracking step in the secondary recrystallization annealing step may be maintained at 1150° C. or higher for 10 hours or more. The cracking step has the purpose of removing C, N and S that are distributed in the steel and cause self-aging, and in order to improve the low magnetic field characteristics, the content of each component needs to be lowered to 0.0015 wt% or less. If, during the cracking step, the cracking temperature is less than 1150° C. or the cracking time is less than 10 hours, it may be difficult to control the contents of C, N and S.

이후, 필요에 따라, 상기와 같이 얻어지는 방향성 전기강판에 대하여 그 표면에 절연피막을 형성할 수도 있다. 상기 절연피막의 예로는 포스테라이트 피막을 이용할 수 있다.Thereafter, if necessary, an insulating film may be formed on the surface of the grain-oriented electrical steel sheet obtained as described above. As an example of the insulating film, a forsterite film may be used.

이하, 실시예를 통해 본 발명을 보다 상세히 설명한다. 다만, 하기 실시예는 본 발명을 보다 상세하게 설명하기 위한 예시일 뿐, 본 발명의 권리범위를 한정하지 않는다.Hereinafter, the present invention will be described in more detail through examples. However, the following examples are only examples for explaining the present invention in more detail, and do not limit the scope of the present invention.

(실시예 1)(Example 1)

중량%로, Si: 3.15%, C: 0.052%, Mn: 0.105%, Al: 0.028%, N: 0.0045% 및 S: 0.0045%를 포함하고, 잔부가 Fe 및 기타 불순물을 포함하는 강 슬라브를 준비하였다. 상기 강 슬라브를 1150℃에서 가열하고 이어 2.6m 두께로 열간압연하여 열연판을 제조하였다. 이 열연판을 1050℃ 이상의 온도로 가열한 후 910℃에서 90초간 유지하고 수냉한 후 산세하였다. 이어서 리버스(Reverse) 압연기를 이용하여, 0.27mm 두께까지 냉간 압연하여 냉연판을 제조하였다. 이 냉연판을 65℃의 이슬점 온도 분위기에서 860℃로 120초간 유지하여 1차 재결정 소둔을 하였다. 이후 MgO를 도포한 다음, 코일 형태로 권취한 뒤, 2차 재결정 소둔하였다. 이 때, 2차 재결정 소둔 과정 중, 750℃부터 1210℃까지 가열함에 있어, 1차 및 2차 승온 속도를 하기 표 1과 같이 제어하였으며, 균열은 1210℃에서 20시간 유지하는 것으로 행하였으며, 이후 노냉하여 방향성 전기강판을 제조하였다. 이와 같이 제조된 방향성 전기강판의 합금조성은 중량%로, Si: 3.15%, C: 0.0012%, Mn: 0.105%, Al: 0.028%, N: 0.001% 및 S: 0.001%를 포함하였다. 이와 같이 제조된 방향성 전기강판에 대하여 자속밀도 및 철손을 측정하여 하기 표 1에 기재하였다.Prepare a steel slab containing Si: 3.15%, C: 0.052%, Mn: 0.105%, Al: 0.028%, N: 0.0045% and S: 0.0045% by weight%, the balance containing Fe and other impurities did. The steel slab was heated at 1150° C. and then hot rolled to a thickness of 2.6 m to prepare a hot-rolled sheet. The hot-rolled sheet was heated to a temperature of 1050° C. or higher, maintained at 910° C. for 90 seconds, cooled with water, and then pickled. Then, using a reverse rolling mill, cold rolling was performed to a thickness of 0.27 mm to prepare a cold rolled sheet. Primary recrystallization annealing was performed by holding this cold-rolled sheet at 860°C for 120 seconds in an atmosphere of 65°C dew point temperature. Thereafter, MgO was applied, and then wound up in a coil shape, followed by secondary recrystallization annealing. At this time, during the secondary recrystallization annealing process, in heating from 750 ° C to 1210 ° C, the primary and secondary temperature increase rates were controlled as shown in Table 1 below, and cracking was performed by maintaining at 1210 ° C. for 20 hours, and then A grain-oriented electrical steel sheet was manufactured by furnace cooling. The alloy composition of the grain-oriented electrical steel sheet prepared as described above was, by weight%, Si: 3.15%, C: 0.0012%, Mn: 0.105%, Al: 0.028%, N: 0.001% and S: 0.001%. The magnetic flux density and iron loss of the grain-oriented electrical steel sheet thus prepared were measured and shown in Table 1 below.

자기특성은 Epstein 측정법을 이용하여 측정하였고, 자속밀도는 800A/m의 자기장 하에서 유도되는 자속밀도의 크기(Tesla)를 측정하였으며, 철손은 인가자장의 크기가 1.3T, 1.5T 및 1.7T이며, 주파수가 50Hz인 조건에서 각각 측정하였다.The magnetic properties were measured using the Epstein measurement method, the magnetic flux density was measured by the magnitude (Tesla) of the magnetic flux density induced under a magnetic field of 800A/m, and the iron loss was 1.3T, 1.5T and 1.7T in the applied magnetic field, Each was measured under the condition that the frequency was 50 Hz.

시편No.Psalm No. 1차 승온 속도
(℃/hr)1st temperature increase rate
(℃/hr) 2차 승온 속도
(℃/hr)Secondary temperature increase rate
(℃/hr) 2차 승온
개시온도
(℃)2nd temperature rise
start temperature
(℃) 자속밀도
(B8, Tesla)magnetic flux density
(B 8 , Tesla) 철손 (W13/50, W/kg)Iron loss (W13/50, W/kg) 철손 (W15/50, W/kg)Iron loss (W15/50, W/kg) 철손 (W17/50, W/kg)Iron loss (W17/50, W/kg) 비고remark 1One 33 66 10501050 1.8651.865 0.5830.583 0.7610.761 0.9650.965 비교예1Comparative Example 1 22 88 33 10301030 1.9421.942 0.4810.481 0.6420.642 0.8650.865 발명예1Invention Example 1 33 88 33 11501150 1.9281.928 0.5450.545 0.7110.711 0.9200.920 비교예2Comparative Example 2 44 88 66 820820 1.9051.905 0.5380.538 0.7050.705 0.9180.918 비교예3Comparative Example 3 55 1010 44 950950 1.9431.943 0.5130.513 0.6840.684 0.8760.876 비교예4Comparative Example 4 66 1010 44 10101010 1.9451.945 0.4860.486 0.6270.627 0.8720.872 발명예2Invention Example 2 77 1010 55 10451045 1.9511.951 0.4610.461 0.6390.639 0.8540.854 발명예3Invention example 3 88 1010 1212 10451045 1.9161.916 0.5340.534 0.7020.702 0.9070.907 비교예5Comparative Example 5 99 1313 33 10801080 1.9431.943 0.4830.483 0.6520.652 0.8680.868 발명예4Invention Example 4 1010 1313 66 10251025 1.9481.948 0.4870.487 0.6430.643 0.8630.863 발명예5Invention Example 5 1111 1818 88 11201120 1.9211.921 0.5320.532 0.6990.699 0.9110.911 비교예6Comparative Example 6 1212 2020 55 10101010 1.9421.942 0.5170.517 0.6820.682 0.8690.869 비교예7Comparative Example 7 1313 88 88 -- 1.8831.883 0.5780.578 0.7480.748 0.9710.971 비교예8Comparative Example 8 1414 1212 1212 -- 1.9111.911 0.5350.535 0.7130.713 0.9130.913 비교예9Comparative Example 9

상기 표 1을 통해 알 수 있듯이, 2차 재결정 소둔 과정에서 있어 승온 속도를 두 단계로 하고, 1차 및 2차 승온 속도와 2차 승온 개시온도를 본 발명이 제안하는 바와 같이 적절히 조절한 발명예 1 내지 5의 경우에는 저자장 철손이 우수함과 동시에 자속밀도(B8)가 1.94T 이상인 것을 확인할 수 있다. As can be seen from Table 1 above, in the secondary recrystallization annealing process, the temperature increase rate is set to two steps, and the primary and secondary temperature increase rate and the secondary temperature increase start temperature are appropriately adjusted as suggested by the present invention. In the case of 1 to 5, it can be confirmed that the low magnetic field iron loss is excellent and the magnetic flux density (B 8 ) is 1.94T or more.

반면, 본 발명이 제안하는 조건을 만족하지 않는 비교예 1 내지 9의 경우에는 1.94T 이상의 자속밀도(B8)를 확보하지 못하거나, 자속밀도(B8)가 높음에도 불구하고 저자장 철손이 열위함을 확인할 수 있다.On the other hand, in the case of Comparative Examples 1 to 9 that do not satisfy the conditions proposed by the present invention, the magnetic flux density (B 8 ) of 1.94T or more cannot be secured, or the low magnetic field iron loss is high despite the high magnetic flux density (B 8 ). inferiority can be seen.

(실시예 2)(Example 2)

실시예 1을 통해 제조된 방향성 전기강판 중 일부를 20부피% 농도 및 50℃로 가열된 염산에 10분간 침적하여 표면에 형성된 베이스코팅을 제거한 뒤, 결정립 입경을 측정하여 하기 표 2에 기재하였다. A portion of the grain-oriented electrical steel sheet prepared in Example 1 was immersed in hydrochloric acid heated to a concentration of 20% by volume and hydrochloric acid heated to 50° C. for 10 minutes to remove the base coating formed on the surface, and then the grain size was measured and shown in Table 2 below.

시편No.Psalm No. 압연면을 기준으로 입자 지름 100mm 이상인 결정립(조대립)이 차지하는 면적 비율(%)Percentage of area occupied by crystal grains (coarse grains) with a grain diameter of 100 mm or more based on the rolling surface (%) 비고remark 22 99 발명예1Invention Example 1 55 2323 비교예4Comparative Example 4 66 1414 발명예2Invention Example 2 77 77 발명예3Invention example 3 99 1111 발명예4Invention Example 4 1212 2626 비교예7Comparative Example 7

상기 표 2를 통해 알 수 있듯이, 본 발명이 제안하는 조건을 만족하는 발명예 1 내지 4의 경우에는 압연면을 기준으로 입자 지름 100mm 이상인 결정립(조대립)이 차지하는 면적 비율이 20% 이하임을 알 수 있는 반면, 본 발명이 제안하는 조건을 만족하지 않는 비교예 4 및 7 경우에는 압연면을 기준으로 입자 지름 100mm 이상인 결정립(조대립)이 차지하는 면적 비율이 20%를 초과함을 확인할 수 있다.As can be seen from Table 2, in the case of Inventive Examples 1 to 4 satisfying the conditions proposed by the present invention, it can be seen that the area ratio occupied by crystal grains (coarse grains) having a particle diameter of 100 mm or more based on the rolling surface is 20% or less On the other hand, in Comparative Examples 4 and 7, which do not satisfy the conditions suggested by the present invention, it can be confirmed that the area ratio occupied by crystal grains (coarse grains) having a particle diameter of 100 mm or more based on the rolling surface exceeds 20%.

Claims (13)

중량%로, Si: 3.0~4.5%, Mn: 0.05~0.2%, Al: 0.015~0.035%, C: 0.0015% 이하(0%는 제외), N: 0.0015% 이하(0%는 제외) 및 S: 0.0015% 이하(0%는 제외), 잔부 Fe 및 기타 불가피한 불순물을 포함하며, 하기 관계식 1 및 2를 만족하는 방향성 전기강판.
[관계식 1] (W13/50/W17/50) ≤ 0.57
[관계식 2] (W15/50/W17/50) ≤ 0.76
(단, 상기 관계식 1에서 Wx/y는 인가자장의 크기가 x/10T이고, 주파수 yHz 조건에서의 철손값을 나타낸다.)
In wt%, Si: 3.0 to 4.5%, Mn: 0.05 to 0.2%, Al: 0.015 to 0.035%, C: 0.0015% or less (excluding 0%), N: 0.0015% or less (excluding 0%), and S : Grain-oriented electrical steel sheet that contains 0.0015% or less (excluding 0%), the remainder Fe and other unavoidable impurities, and satisfies the following Relations 1 and 2.
[Relational Expression 1] (W 13/50 /W 17/50 ) ≤ 0.57
[Expression 2] (W 15/50 / W 17/50 ) ≤ 0.76
(However, in Relation 1, Wx/y represents an iron loss value under the condition that the magnitude of the applied magnetic field is x/10T and the frequency yHz.)
 청구항 1에 있어서,
상기 방향성 전기강판은 자속밀도가 1.94T 이상인 방향성 전기강판.
The method according to claim 1,
The grain-oriented electrical steel sheet has a magnetic flux density of 1.94T or more.
 청구항 1에 있어서,
상기 방향성 전기강판은 압연면을 기준으로 입자 지름 100mm 이상인 결정립이 차지하는 면적 비율이 20% 이하인 방향성 전기강판.
The method according to claim 1,
The grain-oriented electrical steel sheet is a grain-oriented electrical steel sheet in which the area ratio occupied by crystal grains having a particle diameter of 100 mm or more based on the rolling surface is 20% or less.
 중량%로, Si: 3.0~4.5%, Mn: 0.05~0.2%, Al: 0.015~0.035%, C: 0.005~0.1%, N: 0.005% 이하(0%는 제외) 및 S: 0.005% 이하(0%는 제외), 잔부 Fe 및 기타 불가피한 불순물을 포함하는 강 슬라브를 가열하는 단계;
상기 가열된 강 슬라브를 열간압연하여 열연판을 얻는 단계;
상기 열연판을 냉간압연하여 냉연판을 얻는 단계;
상기 냉연판을 1차 재결정 소둔하는 단계; 및
상기 1차 재결정 소둔된 냉연판을 2차 재결정 소둔하는 단계;를 포함하며,
상기 2차 재결정 소둔하는 단계는 승온 및 균열 단계를 포함하고,
상기 승온 단계는 1차 승온 및 2차 승온을 포함하며,
상기 1차 승온 및 2차 승온시, 1차 승온 속도와 2차 승온 속도는 하기 관계식 3을 만족하고,
상기 1차 승온 속도는 5~15℃/hr이며,
상기 균열시, 1150℃ 이상에서 10시간 이상 유지하는 방향성 전기강판의 제조방법.
[관계식 3] (1차 승온 속도) ≥ 2×(2차 승온 속도)
In wt%, Si: 3.0 to 4.5%, Mn: 0.05 to 0.2%, Al: 0.015 to 0.035%, C: 0.005 to 0.1%, N: 0.005% or less (excluding 0%) and S: 0.005% or less ( 0%), heating the steel slab containing the remainder Fe and other unavoidable impurities;
obtaining a hot-rolled sheet by hot rolling the heated steel slab;
cold-rolling the hot-rolled sheet to obtain a cold-rolled sheet;
primary recrystallization annealing the cold-rolled sheet; and
Including; secondary recrystallization annealing of the cold-rolled sheet subjected to the primary recrystallization annealing;
The secondary recrystallization annealing includes a temperature increase and a cracking step,
The temperature raising step includes a first temperature increase and a secondary temperature increase,
When the first temperature increase and the second temperature increase, the first temperature increase rate and the second temperature increase rate satisfy the following relational expression 3
The first temperature increase rate is 5 ~ 15 ℃ / hr,
During the cracking, a method of manufacturing a grain-oriented electrical steel sheet maintained at 1150° C. or higher for at least 10 hours.
[Relational Expression 3] (1st temperature increase rate) ≥ 2×(2nd temperature increase rate)
 청구항 4에 있어서,
상기 강 슬라브 가열시, 가열 온도는 1000~1280℃인 방향성 전기강판의 제조방법.
5. The method according to claim 4,
When heating the steel slab, the heating temperature is 1000 ~ 1280 ℃ method of manufacturing a grain-oriented electrical steel sheet.
 청구항 4에 있어서,
상기 열간압연시, 마무리온도는 950℃이하인 방향성 전기강판의 제조방법.
5. The method according to claim 4,
When the hot rolling, the finishing temperature is 950 ℃ or less method of manufacturing a grain-oriented electrical steel sheet.
 청구항 4에 있어서,
상기 열연판을 얻는 단계 후, 상기 열연판을 수냉한 뒤, 600℃이하에서 권취하는 단계를 추가로 포함하는 방향성 전기강판의 제조방법.
5. The method according to claim 4,
After obtaining the hot-rolled sheet, after cooling the hot-rolled sheet with water, the method of manufacturing a grain-oriented electrical steel sheet further comprising the step of winding at 600 ℃ or less.
 청구항 4에 있어서,
상기 열연판을 얻는 단계 후, 900℃이상에서 열연판 소둔하는 단계를 추가로 포함하는 방향성 전기강판의 제조방법.
5. The method according to claim 4,
After obtaining the hot-rolled sheet, the method of manufacturing a grain-oriented electrical steel sheet further comprising the step of annealing the hot-rolled sheet at 900 ℃ or higher.
 청구항 4에 있어서,
상기 1차 재결정 소둔은 이슬점 온도가 50~70℃인 분위기에서 850~950℃의 온도로 행하여지는 방향성 전기강판의 제조방법.
5. The method according to claim 4,
The primary recrystallization annealing is a method of manufacturing a grain-oriented electrical steel sheet that is performed at a temperature of 850 to 950 ℃ in an atmosphere having a dew point temperature of 50 to 70 ℃.
 청구항 4에 있어서,
상기 1차 승온시, 시작 온도는 700~800℃인 방향성 전기강판의 제조방법.
5. The method according to claim 4,
When the first temperature rise, the starting temperature is 700 ~ 800 ℃ method of manufacturing a grain-oriented electrical steel sheet.
 청구항 4에 있어서,
상기 2차 승온시, 시작 온도는 1000~1100℃인 방향성 전기강판의 제조방법.
5. The method according to claim 4,
When the secondary temperature rises, the starting temperature is 1000 ~ 1100 ℃ method of manufacturing a grain-oriented electrical steel sheet.
 청구항 4에 있어서,
상기 2차 승온시, 승온 속도는 7.5℃/hr이하인 방향성 전기강판의 제조방법.
5. The method according to claim 4,
The second temperature increase, the temperature increase rate is 7.5 ℃ / hr or less method of manufacturing a grain-oriented electrical steel sheet.
 청구항 4에 있어서,
상기 2차 재결정 소둔 단계 후, 2차 재결정 소둔된 냉연판의 표면에 절연 피막을 형성하는 단계를 추가로 포함하는 방향성 전기강판의 제조방법.

5. The method according to claim 4,
After the secondary recrystallization annealing step, the method of manufacturing a grain-oriented electrical steel sheet further comprising the step of forming an insulating film on the surface of the cold-rolled sheet subjected to the secondary recrystallization annealing.
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